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第三章 DAO模式《分层》 ② 代码

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第三章 DAO模式《分层》 ② 代码

1.用户登录管理系统（拓展：图书管理）0723

创建表 users、book

#创建用户表
create table users
(
	userId int primary key auto_increment,
	userName varchar(20),
	password varchar(20),
	nikeName varchar(20),
	sex varchar(5),
	phone varchar(20)
);

select  * from users;

create table book
(
	bookId int primary key auto_increment,
	bookName varchar(200),
	author varchar(20),
	price decimal(5,1),
	pubDate date
);

select * from book;

添加jar包: 数据库jar包，并引用

在这里插入图片描述

项目代码：

util

BaseDAO.java

package com.yzh7.util;

import java.sql.*;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class BaseDAO {

	//四大金刚
	//驱动类
	private static final String DRIVER="com.mysql.cj.jdbc.Driver";
	//连接地址
	private static final String URL="jdbc:mysql://localhost:3306/0723_db?useSSL=false&characterEncoding=utf8&serverTimezone=Asia/Shanghai";
	//用户名
	private static final String USER="root";
	//密码
	private static final String PASSWORD="123456";

	//获取连接
	public static Connection getConnection(){

		Connection con = null;

		try{
			//加载驱动类
			Class.forName(DRIVER);
			//获取连接
			con = DriverManager.getConnection(URL,USER,PASSWORD);
			
		}catch(Exception ex){
			ex.printStackTrace();
		}

		return con;
	}

	//关闭数据库对象
	public static void closeAll(Connection con,Statement st,ResultSet rs){
		
		if(rs!=null){
			try{
				rs.close();
			}catch(Exception ex){
				ex.printStackTrace();
			}
			
		}

		if(st!=null){

			try{
				st.close();
			}catch(Exception ex){
				ex.printStackTrace();
			}
			
		}

		if(con!=null){
			try{
				con.close();
			}catch(Exception ex){
				ex.printStackTrace();
			}
			
		}

	}


	//通用设置参数方法
	public static void setParams(PreparedStatement pst,Object[] params){

		if(params==null){
			return;
		}

		for(int i=0;i<params.length;i++){
			try{
				pst.setObject(i+1,params[i]);
			}catch(Exception ex){
				ex.printStackTrace();
			}
		}
	}


	//通用增删改
	public static int executeUpdate(String sql,Object[] params){

		Connection con = null;
		PreparedStatement pst = null;
		
		int res = -1;
		
		try{

			//获取连接
			con = getConnection();
			//创建预编译命令执行对象
			pst = con.prepareStatement(sql);
			//设置参数
			setParams(pst,params);
			//执行
			res = pst.executeUpdate();

		}catch(Exception ex){
			ex.printStackTrace();
		}finally{
			closeAll(con,pst,null);
		}
		
		return res;
	}


	//通用查询
	public static List<Map<String,Object>> executeQuery(String sql,Object[] params) {

		List<Map<String,Object>> rows = new ArrayList<>();

		Connection con = null;
		PreparedStatement pst = null;
		ResultSet rs = null;

		try{
			//获取连接	
			con = getConnection();			
			//获取命令对象
			pst = con.prepareStatement(sql);
			//设置参数
			setParams(pst,params);
			//执行查询
			rs = pst.executeQuery();

			//通过rs获取结果集的结构信息
			ResultSetMetaData rsmd =  rs.getMetaData();
			//获取结果集的列数
			int colCount = rsmd.getColumnCount();

			//遍历查询结果，并封装到List<Map>中
			while(rs.next()){
				//用Map存储当前行的各个列数据
				Map<String,Object> map = new HashMap<>();
				//循环获取每一列的信息
				for(int i=1;i<=colCount;i++){
					//获取列名(使用rsmd)
					String colName = rsmd.getColumnLabel(i);
					//获取列值(使用rs)
					Object colVal = rs.getObject(i);
					//将当前列存储到map中
					map.put(colName,colVal);								
				}
				
				//将遍历的当前行的数据存储到List中
				rows.add(map);
							
			}


		}catch(Exception ex){
			ex.printStackTrace();
		}finally{
			closeAll(con,pst,rs);
		}
		
		return rows;

	}

}

entity

Users.java

package com.yzh7.entity;

/**
 * @author: hy
 * @create: 2022-07-23 10:54:27
 */
public class Users {
    //编号
    private Integer userId;
    //用户名
    private String userName;
    //密码
    private String password;
    //昵称
    private String nickName;
    //性别
    private String sex;
    //手机
    private String phone;

    public Users() {
    }

    public Users(Integer userId, String userName, String password, String nickName, String sex, String phone) {
        this.userId = userId;
        this.userName = userName;
        this.password = password;
        this.nickName = nickName;
        this.sex = sex;
        this.phone = phone;
    }

    public Integer getUserId() {
        return userId;
    }

    public void setUserId(Integer userId) {
        this.userId = userId;
    }

    public String getUserName() {
        return userName;
    }

    public void setUserName(String userName) {
        this.userName = userName;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public String getNickName() {
        return nickName;
    }

    public void setNickName(String nickName) {
        this.nickName = nickName;
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    public String getPhone() {
        return phone;
    }

    public void setPhone(String phone) {
        this.phone = phone;
    }

    @Override
    public String toString() {
        return "Users{" +
                "userId=" + userId +
                ", userName='" + userName + '\'' +
                ", password='" + password + '\'' +
                ", nickName='" + nickName + '\'' +
                ", sex='" + sex + '\'' +
                ", phone='" + phone + '\'' +
                '}';
    }
}

Book.java

package com.yzh7.entity;

/**
 * @author: hy
 * @create: 2022-07-23 11:57:07
 */
public class Book {
}

dao

IUsersDAO.java

package com.yzh7.dao;

import com.yzh7.entity.Users;

import java.util.List;
import java.util.Map;

/**
 * 数据访问层用户接口
 */
public interface IUsersDAO {
    //根据用户名和密码查询用户账号
    Users getByUserNameAndPassword(String userName, String password);
    //根据用户名查询数据，判断用户名是否存在
    boolean getByUserName(String userName);
    //根据手机查询数据,判断手机是否存在
    boolean getByPhone(String phone);
    //添加用户
    int insert(Users users);

}

IBookDAO.java

package com.yzh7.dao;

import com.yzh7.entity.Book;

import java.util.List;
import java.util.Map;

/**
 * @author: hy
 * @create: 2022-07-23 11:57:35
 */
public interface IBookDAO {
    //查询所有
    List<Map<String,Object>> list();
    int insert(Book book);
    int update(Book book);
    int delete(Integer bookId);
}

impl

UsersDAOImpl.java
package com.yzh7.dao.impl;

import com.yzh7.dao.IUsersDAO;
import com.yzh7.entity.Users;
import com.yzh7.util.BaseDAO;

import java.util.List;
import java.util.Map;

/**
 * 数据访问层实现类
 * @author: hy
 * @create: 2022-07-23 11:03:52
 */
public class UsersDAOImpl implements IUsersDAO {
    /**
     * 根据用户名和密码查询账号
     * @param userName
     * @param password
     * @return
     */
    @Override
    public Users getByUserNameAndPassword(String userName, String password) {
        String sql = "select userId,userName,password,nickName,sex,phone " +
                "     from users " +
                "     where userName = ? and password = ? ";

        Object[] params = {userName,password};

        //条件查询
        List<Map<String,Object>> rows =  BaseDAO.executeQuery(sql,params);

        //如果有数据，则封装查询结果，返回users对象
        if(rows.size()>0){
            //获取集合中的第一条
            Map<String,Object> map = rows.get(0);
            //将Map中的数据，转为Users对象
            Users users = new Users();
            users.setUserId((Integer) map.get("userId"));
            users.setUserName((String) map.get("userName"));
            users.setPassword((String) map.get("password"));
            users.setNickName((String) map.get("nickName"));
            users.setSex((String) map.get("sex"));
            users.setPhone((String) map.get("phone"));

            return users;
        }
        //账号密码不正确，则返回空
        return null;
    }

    /**
     * 校验账号是否存在
     * @param userName
     * @return
     */
    @Override
    public boolean getByUserName(String userName) {
        String sql = "select userId,userName,password,nickName,sex,phone " +
                "     from users " +
                "     where userName = ? ";
        Object[] params = {userName};
        List<Map<String,Object>> rows = BaseDAO.executeQuery(sql,params);
        //返回对应的账号是否存在
        return rows.size()>0;
    }

    /**
     * 校验手机是否存在
     * @param phone
     * @return
     */
    @Override
    public boolean getByPhone(String phone) {
        String sql = "select userId,userName,password,nickName,sex,phone " +
                "     from users " +
                "     where phone = ? ";
        Object[] params = {phone};
        List<Map<String,Object>> rows = BaseDAO.executeQuery(sql,params);
        return rows.size()>0;
    }

    /**
     * 插入数据
     * @param users
     * @return
     */
    @Override
    public int insert(Users users) {
        String sql = "insert into users " +
                "     (userName,password,nickName,sex,phone)" +
                "     values" +
                "     (?,?,?,?,?)";
        Object[] params = {
                users.getUserName(),
                users.getPassword(),
                users.getNickName(),
                users.getSex(),
                users.getPhone()
        };
        return BaseDAO.executeUpdate(sql,params);
    }
}
BookDAOImpl.java
package com.yzh7.dao.impl;

import com.yzh7.dao.IBookDAO;
import com.yzh7.entity.Book;

import java.util.List;
import java.util.Map;

/**
 * @author: hy
 * @create: 2022-07-23 11:58:35
 */
public class BookDAOImpl implements IBookDAO {
    @Override
    public List<Map<String, Object>> list() {
        return null;
    }

    @Override
    public int insert(Book book) {
        return 0;
    }

    @Override
    public int update(Book book) {
        return 0;
    }

    @Override
    public int delete(Integer bookId) {
        return 0;
    }
}

service

IUsersService.java

package com.yzh7.service;

/**
 * 定义用户业务层接口
 */
public interface IUsersService {
    //登陆业务
    boolean login();
    //注册业务
    boolean regist();
}

IBookService.java

package com.yzh7.service;

import com.yzh7.entity.Book;

import java.util.List;
import java.util.Map;

/**
 * @author: hy
 * @create: 2022-07-23 11:58:57
 */
public interface IBookService {
    List<Map<String,Object>> list();
    int add(Book book);
    int update(Book book);
    int delete(Integer bookId);
}

impl

UsersServiceImpl.java
package com.yzh7.service.impl;

import com.mysql.cj.util.StringUtils;
import com.yzh7.dao.IUsersDAO;
import com.yzh7.dao.impl.UsersDAOImpl;
import com.yzh7.entity.Users;
import com.yzh7.service.IUsersService;

import java.util.Scanner;

/**
 * 用户业务的实现类
 * @author: hy
 * @create: 2022-07-23 11:22:36
 */
public class UsersServiceImpl implements IUsersService {

    @Override
    public boolean login() {
        //1.输入账号和密码
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入用户名:");
        String userName = scanner.next();
        System.out.println("请输入密码:");
        String password = scanner.next();

        //2.校验账号密码是否为空
        if(StringUtils.isNullOrEmpty(userName.trim())){
            System.out.println("用户名不能为空");
            return  false;
        }

        if(StringUtils.isNullOrEmpty(password.trim())){
            System.out.println("密码不能为空");
            return false;
        }

        //3.查询对应的账号密码是否存在
        //创建数据访问层对象，调用对用的方法，完成业务需要
        IUsersDAO usersDAO = new UsersDAOImpl();
        Users users =  usersDAO.getByUserNameAndPassword(userName,password);
        if(users==null){
            System.out.println("账号和密码不正确....");
            return false;
        }
        System.out.println("登陆成功....");
        return true;
    }

    @Override
    public boolean regist() {
        //1.输入注册信息
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入用户名:");
        String userName= scanner.next();
        System.out.println("请输入密码:");
        String password = scanner.next();
        System.out.println("请输入昵称:");
        String nickName = scanner.next();
        System.out.println("请输入性别:");
        String sex = scanner.next();
        System.out.println("请输入手机:");
        String phone = scanner.next();

        //2.校验数据是否为空
        if(StringUtils.isNullOrEmpty(userName.trim())){
            System.out.println("用户名不能为空");
            return  false;
        }

        if(StringUtils.isNullOrEmpty(password.trim())){
            System.out.println("密码不能为空");
            return false;
        }

        //....
        //3.唯一性校验:判断用户名是否唯一，判断手机是否唯一
        IUsersDAO usersDAO =new UsersDAOImpl();
        if(usersDAO.getByUserName(userName)){
            System.out.println("该用户名已经存在，不能使用...");
            return false;
        }

        if(usersDAO.getByPhone(phone)){
            System.out.println("该手机已经备使用，不能再次使用....");
            return false;
        }

        //4.插入数据，完成注册
        Users users = new Users();
        users.setUserName(userName);
        users.setPassword(password);
        users.setSex(sex);
        users.setPhone(phone);
        users.setNickName(nickName);
        //使用数据访问层插入数据
        int count = usersDAO.insert(users);
        if(count==1){
            System.out.println("注册成功");
            return true;
        }
        System.out.println("注册失败");
        return false;
    }
}
BookServiceImpl.java
package com.yzh7.service.impl;

import com.yzh7.dao.IBookDAO;
import com.yzh7.dao.impl.BookDAOImpl;
import com.yzh7.entity.Book;
import com.yzh7.service.IBookService;

import java.util.List;
import java.util.Map;

/**
 * @author: hy
 * @create: 2022-07-23 12:00:16
 */
public class BookServiceImpl implements IBookService {
    IBookDAO bookDAO = new BookDAOImpl();

    @Override
    public List<Map<String, Object>> list() {
        return bookDAO.list();
    }

    @Override
    public int add(Book book) {
        return bookDAO.insert(book);
    }

    @Override
    public int update(Book book) {
        return bookDAO.update(book);
    }

    @Override
    public int delete(Integer bookId) {
        return bookDAO.delete(bookId);
    }
}

app

App.java

package com.yzh7.app;

import com.yzh7.service.IUsersService;
import com.yzh7.service.impl.UsersServiceImpl;

import java.util.Scanner;

/**
 * @author: hy
 * @create: 2022-07-23 10:56:21
 */
public class App {

    public static void bookMgr(){

        System.out.println("1.添加 2.修改 3.删除 4.查询 5.退出");

    }

    public static void main(String[] args) {

        System.out.println("==================");
        System.out.println("=欢迎使用图书管理系统=");
        System.out.println("==================");

        Scanner scanner = new Scanner(System.in);

        IUsersService usersService = new UsersServiceImpl();

        while (true) {
            System.out.println("请选择:1.登陆 2.注册 3.退出");
            int choose = scanner.nextInt();
            switch (choose){
                case 1:
                    System.out.println("你选择了登陆...");
                    boolean isLoginSuc =  usersService.login();
                    if(isLoginSuc){
                        System.out.println("进入图书管理系统...");
                        bookMgr();
                    }
                    break;
                case 2:
                    System.out.println("你选择了注册...");
                    boolean isRegitSuc = usersService.regist();
                    break;
                case 3:
                    System.out.println("退出，欢迎下次使用...");
                    return;
                default:
                    System.out.println("选择错误....");
                    break;
            }

        }
    }
}


// A code block
var foo = 'bar';

2.拓展图书管理系统设计（结合课前测0725）

0.确定业务功能,图书管理
------------------
1.建库建表: Book
2.创建java项目
3.添加jar包: 数据库jar包，并引用
4.创建util包，创建BaseDAO工具类
5.创建实体包，创建实体类
  实体包: entity,
  实体类: Book(实体类一般和表名一致)
6.创建数据访问层包/实现包,创建数据访问层接口,创建数据访问层实现类
  数据访问层包:    dao
  数据访问层接口: IBookDAO
  数据访问层实现包: impl
  数据访问层实现类: BookDAOImpl
7.创建业务层包/实现包,业务层接口,业务层实现类
  业务层包: service
  业务层层接口: IBookService
  业务层实现包: impl
  业务层实现类: BookServiceImpl
8.创建程序入口，进行测试

3. 自动代码生成 0725

package com.aaa.code.gen;

/**
 * @author: hy
 * @create: 2022-07-25 10:56:27
 */
public class CodeGenUtil {
    /**
     * 根据数据库类型获取java类型
     * @param dbType
     * @return
     */
    public static String getJavaType(String dbType){
        if("VARCHAR".equalsIgnoreCase(dbType)||
          "CHAR".equalsIgnoreCase(dbType)){
            return "String";
        }else if("DOUBLE".equalsIgnoreCase(dbType)||
                 "FLOAT".equalsIgnoreCase(dbType)||
                 "DECIMAL".equalsIgnoreCase(dbType)){
            return "Double";
        }else if("INT".equalsIgnoreCase(dbType)){
            return "Integer";
        }else if("DATE".equalsIgnoreCase(dbType)){
            return "Date";
        }

        return null;
    }
}

package com.aaa.code.gen;

import com.aaa.util.BaseDAO;

import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;

/**
 * @author: hy
 * @create: 2022-07-25 10:48:41
 */
public class Test {
    public static void main(String[] args) {
        Connection con = null;
        PreparedStatement pst = null;
        ResultSet rs = null;
        String tabName = "Student";

        String sql = "select * from "+tabName+" where 1<>1 ";

        try{
            con = BaseDAO.getConnection();
            pst = con.prepareStatement(sql);
            rs = pst.executeQuery();
            //查询的表结构
            ResultSetMetaData metaData = rs.getMetaData();
            //获取表的列数
            int colCount = metaData.getColumnCount();

            StringBuilder strJavaEntity =new StringBuilder();
            strJavaEntity.append("public class "+tabName+"{\r\n");
            //获取每一个列的信息
            for (int i=1;i<=colCount;i++){
                String colName = metaData.getColumnName(i);
                String colType = metaData.getColumnTypeName(i);
                //System.out.println("private "+CodeGenUtil.getJavaType(colType)+" "+colName+";");
                strJavaEntity.append("\tprivate "+CodeGenUtil.getJavaType(colType)+" "+colName+";\r\n");
            }
            strJavaEntity.append("}");

            System.out.println(strJavaEntity);

            //打印java类内容到磁盘文件
            PrintWriter out = new PrintWriter("D:/"+tabName+".java");
            out.println(strJavaEntity);
            out.flush();
            out.close();

        }catch (Exception ex){
            ex.printStackTrace();
        }finally {
            BaseDAO.closeAll(con,pst,rs);
        }
    }


}

4. log4j的使用(日志工具)

在这里插入图片描述

Project / log4j.properties

### 把日志信息输出到控制台  ###
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
#使用的输出对象
log4j.appender.stdout.Target=System.out
#设置输出内容格式类型
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
#设置格式的具体配置
log4j.appender.stdout.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss} %M %F %p %m%n

### 把日志信息输出到文件：anbo.log ###
#设置输出到文件中
log4j.appender.file=org.apache.log4j.FileAppender
#设置输出文件的文件名
log4j.appender.file.File=test.log
log4j.appender.file.layout=org.apache.log4j.PatternLayout
log4j.appender.file.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss} %l  %m%n

### 把日志信息输出到文件：d:/mylog.txt ###
#设置输出到文件中
log4j.appender.xxx=org.apache.log4j.FileAppender
#设置输出文件的文件名
log4j.appender.xxx.File=d:/mylog.txt
log4j.appender.xxx.layout=org.apache.log4j.PatternLayout
log4j.appender.xxx.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss} %l  %m%n

### 设置优:先级别、以及输出源(多个) ###
log4j.rootLogger=info,stdout,xxx

Project / 代码目录 /…/ MyTest

package com.aaa.test;

import org.apache.log4j.Logger;

/**
 * @author: hy
 * @create: 2022-07-25 11:15:11
 */
public class MyTest {
    public static void main(String[] args) {
        //创建Log4j的日志记录器对象
        Logger logger = Logger.getLogger(MyTest.class);
        // debug<info<warn<error<fatal
        logger.debug("这是debug调试级别的内容");
        logger.info("这是info级别的内容");
        logger.warn("这是warn警告级别的内容");
        logger.error("这是error错误级别的内容");
        logger.fatal("这是fatal严重错误的内容");
    }
}


package com.aaa.test;


import org.apache.log4j.Logger;

import java.util.InputMismatchException;
import java.util.Scanner;

/**
 * @author: hy
 * @create: 2022-07-25 11:33:15
 */
public class MyTest2 {
    public static void main(String[] args) {
        //在什么场景下使用log4j
        Logger log = Logger.getLogger(MyTest2.class);

        log.debug("运算程序开始执行");

        Scanner scanner =new Scanner(System.in);

        try {
            log.debug("准备输入第一个数");
            System.out.println("请输入第一个数:");
            int num1 = scanner.nextInt();
            log.info("输入的第一个数:"+num1);

            log.debug("准备输入第二个数");
            System.out.println("请输入第二个数:");
            int num2 = scanner.nextInt();
            log.info("输入的第二个数:"+num2);

            log.debug("准备运算结果");
            int res = num1/num2;
            log.info("计算结果是:"+res);
            //System.out.println("结果:"+res);
        } catch (ArithmeticException exception) {
            log.error("发生了数学运算异常:"+exception.getMessage());
            exception.printStackTrace();
        } catch (InputMismatchException exception){
            log.error("发生了输入不匹配异常:"+exception.getMessage());
            exception.printStackTrace();
        }

        log.debug("程序执行结束");
    }
}

练习1.用户管理系统设计

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创建表 users

#创建用户表
create table users
(
	userId int primary key auto_increment,
	userName varchar(20),
	password varchar(20),
	nikeName varchar(20),
	sex varchar(5),
	phone varchar(20)
);

select  * from users;

添加jar包

在这里插入图片描述

项目代码：

util

BAO.java

package com.yzh70723.keqiance;

import java.sql.*;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * @author: XYT
 * @create-date: 2022/7/23 9:01
 */
public class BAO {
    private static String driver="com.mysql.cj.jdbc.Driver";
    private static String url="jdbc:mysql://localhost:3306/70723_db1?useSSL=false&characterEncoding=utf8&serverTimezone=Asia/Shanghai";
    private static String user="root";
    private static String password="123456";

    public static Connection getConnection(){
        Connection con=null;

        try {
            Class.forName(driver);
            con= DriverManager.getConnection(url,user,password);
        } catch (ClassNotFoundException e) {
            throw new RuntimeException(e);
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }
        return con;
    }

    public static void closeAll(Connection con, Statement st, ResultSet rs){
        if(rs!=null){
            try {
                rs.close();
            } catch (SQLException e) {
                throw new RuntimeException(e);
            }
        }
        if(st!=null){
            try {
                st.close();
            } catch (SQLException e) {
                throw new RuntimeException(e);
            }
        }
        if(con!=null){
            try {
                con.close();
            } catch (SQLException e) {
                throw new RuntimeException(e);
            }
        }
    }

    public static void setParams(PreparedStatement pst,Object[] params){
        if(params==null){
            return;
        }

        //设置参数
        for (int i = 0; i < params.length; i++) {
            try {
                pst.setObject(i+1,params[i]);
            } catch (SQLException e) {
                throw new RuntimeException(e);
            }
        }
    }

    public static int executeUpdate(String sql, Object[] params){
        Connection con=null;
        PreparedStatement pst=null;

        int res=-1;

        try {
            con=getConnection();
            pst=con.prepareStatement(sql);
            setParams(pst,params);
            res=pst.executeUpdate();
        } catch (SQLException e) {
            throw new RuntimeException(e);
        } finally {
            closeAll(con,pst,null);
        }
        return res;
    }

    public static java.util.List<Map<String, Object>> exeucteQuery(String sql, Object[] params){
        Connection con = null;
        PreparedStatement pst = null;
        ResultSet rs = null;

        List<Map<String, Object>> rows = new ArrayList<>();

        try {
            con = getConnection();
            pst = con.prepareStatement(sql);
            setParams(pst,params);
            rs = pst.executeQuery();

            ResultSetMetaData metaData = rs.getMetaData();
            int colCount = metaData.getColumnCount();

            while (rs.next()){
                Map<String,Object> map = new HashMap<>();
                for(int i=1;i<=colCount;i++){
                    String colName = metaData.getColumnLabel(i);
                    Object colVal = rs.getObject(i);

                    map.put(colName,colVal);
                }
                rows.add(map);
            }
        } catch (SQLException e) {
            throw new RuntimeException(e);
        } finally {
           closeAll(con,pst,rs);
        }
        return rows;

    }

}

entity

Users.java

package com.yzh70723dao.entity;

/**
 * @author: XYT
 * @create-date: 2022/7/24 11:47
 */
public class Users {
    private Integer userId;
    private String userName;
    private String passWord;
    private String nikeName;
    private String sex;
    private String phone;

    public Users() {
    }

    public Users(Integer userId, String userName, String passWord, String nikeName, String sex, String phone) {
        this.userId = userId;
        this.userName = userName;
        this.passWord = passWord;
        this.nikeName = nikeName;
        this.sex = sex;
        this.phone = phone;
    }

    public Integer getUserId() {
        return userId;
    }

    public void setUserId(Integer userId) {
        this.userId = userId;
    }

    public String getUserName() {
        return userName;
    }

    public void setUserName(String userName) {
        this.userName = userName;
    }

    public String getPassWord() {
        return passWord;
    }

    public void setPassWord(String passWord) {
        this.passWord = passWord;
    }

    public String getNikeName() {
        return nikeName;
    }

    public void setNikeName(String nikeName) {
        this.nikeName = nikeName;
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    public String getPhone() {
        return phone;
    }

    public void setPhone(String phone) {
        this.phone = phone;
    }

    @Override
    public String toString() {
        return "Users{" +
                "userId=" + userId +
                ", userName='" + userName + '\'' +
                ", passWord='" + passWord + '\'' +
                ", nikeName='" + nikeName + '\'' +
                ", sex='" + sex + '\'' +
                ", phone='" + phone + '\'' +
                '}';
    }
}

dao

IUsersDAO.java

package com.yzh70723dao.dao;

import com.yzh70723dao.entity.Users;

//数据访问层用户接口
public interface IUsersDAO { //IUsersDAO I 接口标识 Users 针对表名为Users进行操作 DAO 什么层：数据访问层DAO
    //根据用户名和密码查询用户账号
    Users getByUserNameAndPassword(String userName,String password);
    //根据用户名查询数据,判断用户是否存在
    boolean getByUserName(String userName);
    //根据手机查询用户，判断手机是否存在
    boolean getByPhone(String phone);
    //添加用户
    int insert(Users users);


}

impl

UsersDAOImpl.java
package com.yzh70723dao.dao.impl;

import com.yzh70723.keqiance.BAO;
import com.yzh70723dao.dao.IUsersDAO;
import com.yzh70723dao.entity.Users;

import java.util.List;
import java.util.Map;

/**数据访问层实现类
 * @author: XYT
 * @create-date: 2022/7/24 12:24
 */
public class UsersDAOImpl implements IUsersDAO { //实现接口 然后Alt+Insert @Override接口的方法
    //根据用户名和密码，查帐号
    @Override
    public Users getByUserNameAndPassword(String userName, String password) {
        String sql="select userId,userName,password,nikeName,sex,phone"+
                " from users"+
                " where userName=? and password=?";
        Object[] params={userName,password};
        //System.out.println(sql);

        List<Map<String, Object>> rows=BAO.exeucteQuery(sql,params);  //BAO类文件是复制过来的，如果修改的话，原文件也要修改。

        if(rows.size()>0){
            //获取集合中的第一条
            Map<String,Object> map=rows.get(0);
            //将Map中的数据，转为User对象
            Users users=new Users();
            users.setUserId((Integer) map.get("userId")); //强转
            users.setUserName((String) map.get("userName"));
            users.setPassWord((String) map.get("password"));
            users.setNikeName((String) map.get("nikeName"));
            users.setSex((String) map.get("sex"));
            users.setPhone((String) map.get("phone"));

            return users;
        }
        //账号密码不正确，返回空
        return null;
    }
    //校验用户名是否存在
    @Override
    public boolean getByUserName(String userName) {
        String sql="select userId,userName,password,nikeName,sex,phone"+
                " from users"+
                " where userName=?";
        Object[] params={userName};

        List<Map<String, Object>> rows=BAO.exeucteQuery(sql,params);

        return rows.size()>0;
    }
    //校验手机号是否存在
    @Override
    public boolean getByPhone(String phone) {
        String sql="select userId,userName,password,nikeName,sex,phone"+
                " from users"+
                " where phone=?";
        Object[] params={phone};

        List<Map<String, Object>> rows=BAO.exeucteQuery(sql,params);

        return rows.size()>0;
    }

    //插入数据
    @Override
    public int insert(Users users) {
        String sql="insert into users"+
                " (userName,password,nikeName,sex,phone)"+
                " values"+
                " (?,?,?,?,?)";
        Object[] params={users.getUserName(),
                            users.getPassWord(),
                            users.getNikeName(),
                            users.getSex(),
                            users.getPhone()
                        };
        return BAO.executeUpdate(sql,params);
    }
}

service

IUsersService.java

package com.yzh70723dao.service;
//定义用户业务层接口
public interface IUsersService {
    //用户登录
    boolean login();
    //用户注册
    boolean regist();
}

impl

UsersService.java
package com.yzh70723dao.service.impl;

import com.mysql.cj.util.StringUtils;
import com.yzh70723dao.dao.IUsersDAO;
import com.yzh70723dao.dao.impl.UsersDAOImpl;
import com.yzh70723dao.entity.Users;
import com.yzh70723dao.service.IUsersService;

import java.util.Scanner;

/**用户业务的实现类
 * @author: XYT
 * @create-date: 2022/7/24 18:21
 */
public class UsersService implements IUsersService {
    //用户登录
    @Override
    public boolean login() {
        //输入账号和密码
        Scanner scanner=new Scanner(System.in);
        System.out.println("please input userName:");
        String userName=scanner.next();
        System.out.println("please input password:");
        String password=scanner.next();

        //校验账号和密码是否为空
        if(StringUtils.isNullOrEmpty(userName.trim())){
            System.out.println("userName cann't be null!");
            return false;
        }
        if(StringUtils.isNullOrEmpty(password.trim())){
            System.out.println("password cann't be null!");
            return false;
        }

        //不为空，则校验是否在数据库中存在
        IUsersDAO usersDAO=new UsersDAOImpl();
        Users users=usersDAO.getByUserNameAndPassword(userName,password);
        if(users==null){
            System.out.println("userName and password aren't right!");
            return false;
        }
        System.out.println("login sucessifully!");
        return true;
    }
    //用户注册
    @Override
    public boolean regist() {
        //输入信息
        Scanner scanner=new Scanner(System.in);
        System.out.println("please input userName:");
        String  userName=scanner.next();
        System.out.println("please input password:");
        String  password=scanner.next();
        System.out.println("please input nikeName:");
        String  nikeName=scanner.next();
        System.out.println("please input sex:");
        String  sex=scanner.next();
        System.out.println("please input phone:");
        String  phone=scanner.next();
        //校验
        if(StringUtils.isNullOrEmpty(userName.trim())){
            System.out.println("userName cann't be null!");
            return false;
        }
        if(StringUtils.isNullOrEmpty(password.trim())){
            System.out.println("password cann't be null!");
            return false;
        }
        if(StringUtils.isNullOrEmpty(nikeName.trim())){
            System.out.println("nikeName cann't be null!");
            return false;
        }
        if(StringUtils.isNullOrEmpty(sex.trim())){
            System.out.println("sex cann't be null!");
            return false;
        }
        if(StringUtils.isNullOrEmpty(phone.trim())){
            System.out.println("phone cann't be null!");
            return false;
        }
       //唯一性判断 (待完善，其他的列唯一性判断)
        IUsersDAO usersDAO=new UsersDAOImpl(); //上面的步骤也存在，可以定义到外围做全局变量（待完善）
        if(usersDAO.getByUserName(userName)){
            System.out.println("The userName has already exised!");
            return false;
        }
        if(usersDAO.getByUserName(phone)){
            System.out.println("The phone has already exised!");
            return false;
        }
        //插入数据，完成注册
        Users users=new Users();
        users.setUserName(userName);
        users.setPassWord(password);
        users.setNikeName(nikeName);
        users.setSex(sex);
        users.setPhone(phone);
        //使用数据访问层插入数据
        int count=usersDAO.insert(users);
        if(count==1){
            System.out.println("logist successfully!");
            return true;
        }
        System.out.println("logist falsely!");
        return false;

    }
}

APP

package com.yzh70723dao.app;

import com.yzh70723dao.service.IUsersService;
import com.yzh70723dao.service.impl.UsersService;

import java.util.Scanner;

/**
 * @author: XYT
 * @create-date: 2022/7/24 11:52
 */
public class App {
    //模仿入口页面
    public static void main(String[] args) {
        System.out.println("==============");
        System.out.println("Welcome to Tushuguanlisystem.");
        System.out.println("==============");

        Scanner scanner=new Scanner(System.in);

        while(true){
            System.out.println("Please choose：1.denglu 2.zhuce 3.tuichu");
            int choose=scanner.nextInt();

            IUsersService iUsersService=new UsersService();
            switch (choose){
                case 1:
                    System.out.println("you choose denglu...");
                    //IUsersService iUsersService=new UsersService(); //定义到外围(待完善)
                    boolean isLoginSuc=iUsersService.login();
                    if(isLoginSuc){
                        System.out.println("come into system of tushuguanli...");
                        
                    }
                    break;
                case 2:
                    System.out.println("you choose zhuce...");
                    boolean isRegistSuc=iUsersService.regist();
//                    if(isRegistSuc){
//                        System.out.println("come into system of tushuguanli...");
//                    }
                    break;
                case 3:
                    System.out.println("you choose tuichu...");
                    break;
                default:
                    System.out.println("you choose false...");
                    break;
            }

        }
    }
}

课前测 0725

在这里插入图片描述
在这里插入图片描述

创建表student

#学生表:编号，姓名，性别，生日。
create table student
(
		stuId int primary key auto_increment,
		stuName varchar(20),
		sex varchar(20),
		birthday date
);

select * from student;

添加jar包

在这里插入图片描述

项目代码

util

BAO.java

package com.yzh70725keqiance.util;

import java.sql.*;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * @author: XYT
 * @create-date: 2022/7/23 9:01
 */
public class BAO {
    private static String driver="com.mysql.cj.jdbc.Driver";
    private static String url="jdbc:mysql://localhost:3306/70723_db1?useSSL=false&characterEncoding=utf8&serverTimezone=Asia/Shanghai";
    private static String user="root";
    private static String password="123456";

    public static Connection getConnection(){
        Connection con=null;

        try {
            Class.forName(driver);
            con= DriverManager.getConnection(url,user,password);
        } catch (ClassNotFoundException e) {
            throw new RuntimeException(e);
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }
        return con;
    }

    public static void closeAll(Connection con, Statement st, ResultSet rs){
        if(rs!=null){
            try {
                rs.close();
            } catch (SQLException e) {
                throw new RuntimeException(e);
            }
        }
        if(st!=null){
            try {
                st.close();
            } catch (SQLException e) {
                throw new RuntimeException(e);
            }
        }
        if(con!=null){
            try {
                con.close();
            } catch (SQLException e) {
                throw new RuntimeException(e);
            }
        }
    }

    public static void setParams(PreparedStatement pst,Object[] params){
        if(params==null){
            return;
        }

        //设置参数
        for (int i = 0; i < params.length; i++) {
            try {
                pst.setObject(i+1,params[i]);
            } catch (SQLException e) {
                throw new RuntimeException(e);
            }
        }
    }

    public static int executeUpdate(String sql, Object[] params){
        Connection con=null;
        PreparedStatement pst=null;

        int res=-1;

        try {
            con=getConnection();
            pst=con.prepareStatement(sql);
            setParams(pst,params);
            res=pst.executeUpdate();
        } catch (SQLException e) {
            throw new RuntimeException(e);
        } finally {
            closeAll(con,pst,null);
        }
        return res;
    }

    public static List<Map<String, Object>> exeucteQuery(String sql,Object[] params){

        Connection con = null;
        PreparedStatement pst = null;
        ResultSet rs = null;

        List<Map<String, Object>> rows = new ArrayList<>();

        try {
            con = getConnection();
            pst = con.prepareStatement(sql);
            setParams(pst,params);
            rs = pst.executeQuery();

            ResultSetMetaData metaData = rs.getMetaData();
            int colCount = metaData.getColumnCount();

            while (rs.next()){
                Map<String,Object> map = new HashMap<>();
                for(int i=1;i<=colCount;i++){
                    String colName = metaData.getColumnLabel(i);
                    Object colVal = rs.getObject(i);

                    map.put(colName,colVal);
                }
                rows.add(map);
            }
        } catch (SQLException e) {
            throw new RuntimeException(e);
        } finally {
           closeAll(con,pst,rs);
        }
        return rows;

    }

}

entity

Student.java

package com.yzh70725keqiance.entity;

import java.sql.Date;

/**
 * @author: XYT
 * @create-date: 2022/7/25 9:04
 */
public class Student {
    private Integer stuId;
    private String stuName;
    private String sex;
    private Date birthday;

    public Student() {
    }

    public Student(Integer stuId, String stuName, String sex, Date birthday) {
        this.stuId = stuId;
        this.stuName = stuName;
        this.sex = sex;
        this.birthday = birthday;
    }

    public Student(String stuName, String sex, Date birthday) {  //方便使用
        this.stuName = stuName;
        this.sex = sex;
        this.birthday = birthday;
    }

    public Integer getStuId() {
        return stuId;
    }

    public void setStuId(Integer stuId) {
        this.stuId = stuId;
    }

    public String getStuName() {
        return stuName;
    }

    public void setStuName(String stuName) {
        this.stuName = stuName;
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    public Date getBirthday() {
        return birthday;
    }

    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }

    @Override
    public String toString() {
        return "Student{" +
                "stuId=" + stuId +
                ", stuName='" + stuName + '\'' +
                ", sex='" + sex + '\'' +
                ", birthday='" + birthday + '\'' +
                '}';
    }
}

dao

IStudentDAO.java

package com.yzh70725keqiance.dao;

import com.yzh70725keqiance.entity.Student;

import java.util.List;
import java.util.Map;

public interface IStudentDAO {
    List<Map<String, Object>> query();

    int insert(Student student);
    int delect(Student student);
    int update(Student student);

}

impl

StudentDAO.java
package com.yzh70725keqiance.dao.impl;

import com.yzh70725keqiance.dao.IStudentDAO;
import com.yzh70725keqiance.entity.Student;
import com.yzh70725keqiance.util.BAO;

import java.util.List;
import java.util.Map;

/**
 * @author: XYT
 * @create-date: 2022/7/25 9:07
 */
public class StudentDAO implements IStudentDAO {
    @Override
    public List<Map<String, Object>> query() {
        String sql = "select * from student ";
        System.out.println(sql);
        return BAO.exeucteQuery(sql,null);

    }

    @Override
    public int insert(Student student) {
                String sql="insert into student"+
                " (stuName,sex,birthday)"+
                " values"+
                " (?,?,?)";
        Object[] params={student.getStuName(),
                student.getSex(),
                student.getBirthday()
        };
        return BAO.executeUpdate(sql,params);

    }

    @Override
    public int delect(Student student) {
        String sql="delete from student"+
                " where stuId=? ";
        Object[] params={student.getStuId()
        };
        return BAO.executeUpdate(sql,params);
    }

    @Override
    public int update(Student student) {
        String sql="update student"+
                "    set stuName=?,sex=?,birthday=?"+
                "    where stuId=?";

        Object[] params={
                student.getStuName(),
                student.getSex(),
                student.getBirthday(),
                student.getStuId()
        };
        return BAO.executeUpdate(sql,params);
    }

}

service

IStudentService.java

package com.yzh70725keqiance.service;

import com.yzh70725keqiance.entity.Student;

import java.util.List;
import java.util.Map;

public interface IStudentService {

    List<Map<String, Object>> sqery();
    int insert(Student student);
    int delect(Student student);
    int update(Student student);


}

impl

StudentService.java
package com.yzh70725keqiance.service.impl;

import com.yzh70725keqiance.dao.IStudentDAO;
import com.yzh70725keqiance.dao.impl.StudentDAO;
import com.yzh70725keqiance.entity.Student;
import com.yzh70725keqiance.service.IStudentService;

import java.util.List;
import java.util.Map;

/**
 * @author: XYT
 * @create-date: 2022/7/25 9:09
 */
public class StudentService implements IStudentService {
    IStudentDAO studentDAO=new StudentDAO();

    @Override
    public List<Map<String, Object>> sqery() {
        return studentDAO.query();
    }

    @Override
    public int insert(Student student) {
        return studentDAO.insert(student);
    }

    @Override
    public int delect(Student student) {
        return studentDAO.delect(student);
    }

    @Override
    public int update(Student student) {
        return studentDAO.update(student);
    }
}

app

App

package com.yzh70725keqiance.app;

import com.yzh70725keqiance.entity.Student;
import com.yzh70725keqiance.service.IStudentService;
import com.yzh70725keqiance.service.impl.StudentService;

import java.util.List;
import java.util.Map;

/**
 * @author: XYT
 * @create-date: 2022/7/25 9:10
 */
public class App {
    //模仿入口页面
    public static void main(String[] args) {
        IStudentService iStudentService=new StudentService();
        //插入
//        Student student=new Student("zhangsan","nan",java.sql.Date.valueOf("2000-01-01"));
//        iStudentService.insert(student);

//        Student student2=new Student("lisi","nv",java.sql.Date.valueOf("2002-02-02"));
//        iStudentService.insert(student2);

		//插入（带有记录数）
//        Student student=new Student("zhangsan","nan",java.sql.Date.valueOf("2000-01-01"));
//        int res=iStudentService.insert(student);
//        System.out.println("jilushu:"+res);
//
//
//        Student student2=new Student("lisi","nv",java.sql.Date.valueOf("2002-02-02"));
//        int res1=iStudentService.insert(student2);
//        System.out.println("jilushu:"+res1);

        //修改
        Student student3=new Student(1,"zhangsanfeng","nan",java.sql.Date.valueOf("2001-01-01"));
        int res=iStudentService.update(student3);
        System.out.println("jilushu:"+res); //该输出可有可无，但可以帮助我们理解代码的运行

        //Student student4=new Student();

//        Student student = new Student(1,"zhangsanfeng","nan",java.sql.Date.valueOf("2001-01-01"));
//        //改
//        int res = iStudentService.update(student);
//        System.out.println("记录数:"+res);
        //删除
//        int res = iStudentService.delect(student);
//        System.out.println("记录数:"+res);

        //查找
//        List<Map<String, Object>> maps = iStudentService.sqery();
//        //System.out.println(maps);
//        for (Map map :maps){
//            System.out.println(map);

    }
}

运行结果

生成表：
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插入：
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修改：
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查找：
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删除：
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练习2.自从生成代码

package com.yzh70725.zidongshengcheng;

/**
 * @author: XYT
 * @create-date: 2022/7/25 15:01
 */
public class CodeGenUtil {

    //根据数据库获取java类型
    public static String getJavaType(String dbType){
        if("varchar".equalsIgnoreCase(dbType) ||
           "char".equalsIgnoreCase(dbType)){
            return "String";
        } else if ("double".equalsIgnoreCase(dbType)||
                   "float".equalsIgnoreCase(dbType)||
                   "decimal".equalsIgnoreCase(dbType)) {
            return "double";
        } else if ("int".equalsIgnoreCase(dbType)) {
            return "int";
        } else if ("date".equalsIgnoreCase(dbType)) {
            return "date";
        }

        return null;
    }
}

package com.yzh70725.zidongshengcheng;

import java.io.FileNotFoundException;
import java.io.PrintWriter;
import java.sql.*;

/**
 * @author: XYT
 * @create-date: 2022/7/25 15:15
 */
public class Test {
    public static void main(String[] args) {
        Connection con=null;
        PreparedStatement pst=null;
        ResultSet rs=null;
        String tabName="student";

        String sql="select * from "+tabName+" where 1<>1 "; //什么意思？


        try {
            con=BAO.getConnection();
            pst=con.prepareStatement(sql);
            rs=pst.executeQuery();
            //获取结果集对象
            ResultSetMetaData metaData=rs.getMetaData();
            int colCount=metaData.getColumnCount();

            //public StringBuilder append(Object obj) { return append(String.valueOf(obj)); }
            StringBuilder strJavaEntity = new StringBuilder();
            strJavaEntity.append("public class "+tabName+"{\r\n");

            //获取每一列的信息
            for(int i=1;i<=colCount;i++){
                String colName = metaData.getColumnName(i);
                String colType= metaData.getColumnTypeName(i);
                strJavaEntity.append("\tprivate "+CodeGenUtil.getJavaType(colType)+" "+colName+";\r\n");
            }
            strJavaEntity.append("}");

            System.out.println(strJavaEntity);

            //打印java类内容到磁盘文件
            PrintWriter out=new PrintWriter("D:/"+tabName+".java");
            out.println(strJavaEntity);
            out.flush();
            out.close();

        } catch (SQLException e) {
            throw new RuntimeException(e);
        } catch (FileNotFoundException e) {
            throw new RuntimeException(e);
        } finally {
            BAO.closeAll(con,pst,rs);
        }


    }
}

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练习3.log4j的使用（日志工具）

package com.yzh70725.jilu;


import org.apache.log4j.Logger;

/**
 * @author: XYT
 * @create-date: 2022/7/25 12:00
 */
public class Test1 {
    public static void main(String[] args) {
        //创建记录对象
        Logger logger=Logger.getLogger(Test1.class);
        //debug<info<warn<error<fatal 级别
        logger.debug("This is the message of debug");
        logger.info("This is the message of info");
        logger.warn("This is the message of warn");
        logger.error("This is the message of error");
        logger.fatal("This is the message of fatal");
    }
}

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package com.yzh70725.jilu;

import com.yzh70725.zidongshengcheng.Test;
import org.apache.log4j.Logger;

import java.util.InputMismatchException;
import java.util.Scanner;

/**
 * @author: XYT
 * @create-date: 2022/7/25 12:02
 */
public class Test2 {
    public static void main(String[] args) {
        Logger logger=Logger.getLogger(Test2.class);

        logger.debug("Project start!");

        Scanner scanner=new Scanner(System.in);


        try {
            logger.debug("Be ready to input a number");  //debug
            System.out.println("Please input a number:");
            int num1=scanner.nextInt();
            logger.info("The first number:"+num1);  //info

            logger.debug("Be ready to input another number");
            System.out.println("Please input another number:");
            int num2=scanner.nextInt();
            logger.info("The second number:"+num2);

            logger.debug("Being preparing to ruturn result:");
            int res=num1/num2;
            logger.info("The resule is:"+res);
//        } catch (Exception e) {
//            throw new RuntimeException(e);
//        }
        } catch (ArithmeticException exception) {
            logger.error("ERROR:ArithmeticException!"+exception.getMessage()); //发生了数学运算异常
            exception.printStackTrace();
        } catch (InputMismatchException exception) {
            logger.error("ERROR:InputMismatchException!"+exception.getMessage()); //发生了输入不匹配异常
            exception.printStackTrace();
        }
        logger.debug("The project over!");

    }
}

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